Method for the transmission of information in a universal transmission network

ABSTRACT

The combination point (for example, CP 1 ) at which the two last transmission paths are combined or the single transmission path is divided is selected by a central control means (SCP) in the transmission network, which is informed of all combination points (CP 1,  CP 2 ) at which two redundant transmission paths are respectively combined or a single transmission path is divided, as interworking point (IWP) in the transmission network at which mobile radiotelephone network-specifically encoded information contained in the transmission frame are converted into fixed network-specifically encoded information. Given dynamic change of the number of redundant transmission paths (macro diversity), the interworking point for the conversion of the mobile radiotelephone network-specifically encoded information into fixed network-specifically encoded information can be localized and flexibly determined where a combination point combines the last two transmission paths or, respectively, divides the individual transmission path.

BACKGROUND OF THE INVENTION

The invention is directed to a method for the transmission ofinformation in a universal transmission network in which mobileradiotelephone-specific and fixed network-specific functions areimplemented.

The article “Mobilkommunikation auf Expansionskurs”, in telcom report 18(1995), No. 2, pages 52 through 55, discloses universal transmissionnetworks (UMTS Universal Mobile Telecommunications System, FPLMTS FuturePublic Land Mobile Telecommunications System) in which differentnetworks and network services are combined for person-related mobiletelecommunication. A universal access to a transmission network in whichmobile radiotelephone network related and fixed network relatedfunctions are implemented for voice, data and image communicationthereby arises for the network subscribers, whether mobileradiotelephone subscribers or fixed network subscribers.

As known, the radiotelephone station of a network subscriber cantransmit the same information on a plurality of redundant transmissionpaths that are set up parallel via a radio transmission interface fromthe network to the radiotelephone subscriber station or from theradiotelephone subscriber station to the transmission network (macrodiversity) in order to achieve an optimally good transmission quality.This means that the signaling and/or useful information that are usuallyinserted into one or more transmission frames are received by aplurality of radio equipment, for example base transmission/receptionstations of the transmission network. The information transmission viaparallel redundant transmission paths is applied, for example, given aradio transmission interface that uses the CDMA access method (CodeDivision Multiple Access) according to U.S. Pat. No. 5,101,501. Theredundant transmission paths can be dynamically set up and cleared downwhile the radiotelephone subscriber station changes its location. Anoperation in this transmission mode (macro diversity) is also possibleover a longer time span given a stationary radiotelephone subscriberstation.

In an ATM network with a utilization of a radio interface for thetransmission of information from or, respectively, to a mobile station,EP-A-0 679 042 discloses that an improved transmission quality beobtained by a setup of redundant paths by the mobile station. The highertransmission capacity thereby required for the transmission of ATM cellsin the access network between base stations with which the mobilestation is in radio communication and a mobile network interface unit isreduced in that sub-networks are formed in the access network andredundant paths are combined or, respectively, divided in theirinterfaces (sub-network interfaces).

The information that are sent out by the radiotelephone subscriberstation in the transmission frames on various transmission paths can bemerged in the transmission network at combination points at whichrespectively two transmission paths are combined into a singletransmission path in the one transmission direction (uplink) and thesingle transmission path is divided into two transmission paths in theother transmission direction (downlink). The plurality and distributionof the combination points onto network elements of the transmissionnetwork changes dynamically with the addition or, respectively, removalof redundant transmission paths that can be additionally set up or,respectively, in turn cleared down by the radiotelephone subscriberstation.

For a best possible utilization of the network elements of the universaltransmission network, it is necessary to determine a transition point atwhich mobile radiotelephone-specifically encoded information must beconverted into fixed network-specifically encoded information. Since thetransition point terminates all mobile radiotelephone-specificfunctions, a conversion can only ensue following all combination pointsgiven the presence of a plurality of redundant transmission paths in thetransmission network. Changes in the plurality and distribution of thecombination points and, thus, in the determination of the transitionpoint in the transmission network derive due to the dynamic addition andremoval of redundant transmission paths.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to specify a methodwith which the transition point in the transmission network can beflexibly determined given dynamic set up or, respectively, clear down ofredundant transmission paths (macro diversity).

A combination point at which the two last transmission paths arecombined is selected by a central control means of the transmissionnetwork, which is formed of all combination points, as sole combinationpoint in the transmission network at which mobile radiotelephonenetwork-specifically encoded information contained in the transmissionframe are converted into fixed network-specifically encoded information.The transition point for the conversion of the mobile radiotelephonenetwork-specifically encoded information into fixed network-specificallyencoded information can thus by dynamically localized and flexiblydetermined where a combination point combines the last two transmissionpaths or divides the single transmission path. As a result of theinventive method, it is assured given dynamic setup and cleardown ofredundant transmission paths on the radio transmission interface thatthe transition point is located in a network element of a network levelthat lies optimally close to the radiotelephone subscriber station.

Given modification of the transition point caused by a setup of anadditional transmission path or by a cleardown of an existingtransmission path, the combination point that becomes the new transitionpoint according to a development of the invention is requested toimplement the conversion by the central control means in a signalingmessage.

According to another development of the invention, the combination pointthat hitherto implemented the conversion is requested to desist from theconversion by the central control means in a signaling message.

An additional signaling outlay in the form of the signaling messages isrequired for determining the new transition point with the centralcontrol means due to the setup of an additional transmission path or thecleardown of an existing transmission path. However, no additionalinformation with reference whereto the transition point can bedetermined need be entered in the transmission frame therefor.

It is advantageous when a service control location that is involved inthe transmission network for the executive sequencing of services isemployed as central control means.

According to a development of the invention, the transition point can beplaced into a radio equipment or into a switching equipment of theuniversal transmission network.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel,are set forth with particularity in the appended claims. The invention,together with further objects and advantages, may best be understood byreference to the following description taken in conjunction with theaccompanying drawings, in the several Figures of which like referencenumerals identify like elements, and in which:

FIG. 1 two different redundant transmission paths that are combined inthe transmission network at a combination point that is the transitionpoint;

FIG. 2 three redundant transmission paths after setup of an additionaltransmission path that leads to a change of the transition point in thetransmission network;

FIG. 3 the signalling messages in the transmission network givenaddition of an additional transmission path; and

FIG. 4 the signalling messages in the transmission network given removalof an existing transmission path.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a respective block circuit diagram, FIGS. 1 and 2 depict the networkelements of a universal transmission network UNW in which both mobileradiotelephone network-specifically encoded information as well as fixednetwork-specifically encoded information are transmitted forperson-related mobile communication between network subscribers. Theuniversal transmission network UNW enables a person-related mobilecommunication for the network subscribers of different access networkssuch as, for example, mobile radiotelephone network and fixed network,independently of the respective access network. In the present example,the transmission network UNW according to FIG. 1 comprises a pluralityof radio equipment BTS, BTS′, at least one control means BSC and atleast one switching equipment LE as network elements. Of course, furthernetwork elements are present, but these are not necessary for anunderstanding of the invention. The radio equipment BTS, BTS′ receivethe information that are sent to the network from a radiotelephonesubscriber station MS in the upstream transmission direction (uplink)and send the information that are received from the transmission network(downlink) in the downstream transmission direction, respectively via aradio transmission interface. Each radio equipment BTS . . . therebyusually serves a radio cell that represents the smallest radio coveragearea in a cellularly constructed network. Due to the employment ofdirectional antennas at a location of the radio equipment BTS . . . aradio cell can be divided into two or more sectored cells that thenetwork treats like ordinary radio cells.

The control means BSC assumes the radio-oriented control functions inthe transmission network such as, for example, the radio processingfunctions, the administration of the radio equipment, the radio channeladministration, etc. Each control means BSC thereby serves one or moreradio equipment BTS, BTS′. The switching equipment LE that is arrangedin the switching system of the transmission network in addition to otherswitching equipment is connected to the control means BSC. The switchingsystem thereby assumes all mobile radiotelephone network-related andfixed network-related switching functions that relate to the setup andcleardown of call connections, the routing in the universal transmissionnetwork. In the present example, the switching equipment LE is composedof a local switching equipment (local exchange) as employed, forexample, for switching in locally limited areas of a fixed network. Aservice control point SCP that is involved in the transmission networkfor the executive sequencing of services for the network subscribers isconnected to the local exchange LE. As intelligent central controlmeans, it comprises the service logic and the data for theimplementation of the services.

The radio subscriber station MS works in a transmission mode wherein aplurality of redundant transmission paths to the radio equipment are setup parallel at the same point in time for a logical connection (macrodiversity). The setup and cleardown of redundant transmission paths canensues by the network in the downstream transmission direction(downlink) or by the radiotelephone subscriber station in the upstreamtransmission direction (uplink). In the present example, the sameinformation, which are entered in mutually corresponding transmissionframes, are received via the radio transmission interface by the radioequipment BTS, BTS′ in parallel on two redundant transmission paths. Theinformation thereby contain mobile radiotelephone network-specificallyencoded information that can be both signalling information as well asvoice and data information. In that a total of m+1 transmission pathshave been set up parallel from the radiotelephone subscriber station MS,a total of m combination points are required for the combination ofrespectively two transmission paths in the transmission network. Due tothe total of m+1=2 redundant transmission paths, the information of twoincoming transmission frames are respectively combined to information inone outgoing transmission frame at m=1 combination points CP1 in thetransmission network. The information about how many combination pointsare necessary and in which network elements they are located are storedin the central control means SCP and offered by it as needed. Since thecentral control means SCP is informed about all combination points inthe network, it selects the combination point CP1 at which the two lasttransmission paths are combined as transition point (interworking point)IWP in the transmission network at which the mobile radiotelephonenetwork-specifically encoded information contained in the transmissionframe are converted into fixed network-specifically encoded information.

In the present example, the mobile radiotelephone network-specificallyencoded information are located in a transmission frame that is aninformation cell ATM-IC formed according to the asynchronous transfermode (ATM). As known, every ATM information cell ATM-IC comprises aheader field (header) having the length of 5 bytes and an informationfield (payload) having the length of 48 bytes. The mobile radiotelephonenetwork-specifically encoded information can also be transmitted ininformation blocks according to a synchronous or plesiochronic transfermode (SDH or PDH).

FIG. 2 shows a total of three redundant transmission paths, theadditional path thereof compared to FIG. 1 having been added by theradiotelephone subscriber station MS. This means that two redundanttransmission paths lead from the radiotelephone subscriber station MS tothe radio means BTS and BTS′ and a third transmission path leadstherefrom to a further radio means BTS″ via the radio transmissioninterface. The radio means BTS and BTS′ forward the two incomingtransmission frames with the identical information to the control meansBSC on two transmission paths. The radio means BTS″ likewise sends thesame information in the corresponding transmission frame to a furthercontrol means BSC′ via the third transmission path. In the control meansBSC, the identical information incoming on the two transmission pathsare combined at the combination point CP1. The combination point CP1,however, is no longer the interworking point since the number ofcombination points has increased due to the additionally setuptransmission path, so that the last two transmission paths are no longercombined at the combination point CP1.

The information that the control means BSC′ receives on the thirdtransmission path are immediately forwarded to the switching equipmentLE without a combining of redundant transmission paths being required ata combination point in the control means BSC′. The two individualtransmission paths that were set up by the control means BSC and BSC′are combined at a second combination point CP2 in the switchingequipment LE. The information contained in the two incoming transmissionframes are in turn combined and entered into an outgoing transmissionframe that the switching equipment LE sends out on an individualconnection path. The combination point CP2 in the switching equipment LEforms the new interworking point IWP at which the mobile radiotelephonenetwork-specifically encoded information are converted into fixednetwork-specifically encoded information for further processing insucceeding network elements of the transmission network. The centralcontrol means SCP thereby requests that the new interworking point IWPimplement the conversion, whereas the previous interworking point, thecombination point CP1, is informed by the central control means SCP thatthe mobile radiotelephone network-specifically encoded information arenot to be converted. The remain unmodified and are sent to the switchingequipment LE in the outgoing transmission frame. The informationexchange between the central control means SCP and the new interworkingpoint as well as the old interworking point ensues with correspondingsignalling messages.

FIG. 3 shows the signalling flow between the network elements or,respectively, combination points after addition of a furthertransmission path—according to FIG. 2. The central control means SCPtransmits a signalling message IWR to the switching equipment LE inwhich the combination point CP2 is defined as new interworking pointIWP. The signalling message IWR contains the request for the conversionof the mobile radiotelephone network-specifically encoded informationcontained in the transmission frame. The switching equipment LEacknowledges the request for conversion in a signalling message IWRAthat is sent back to the central control means SCP in the oppositedirection. The control means BSC, in which the old interworking pointthat previously implemented the conversion was formed by the combinationpoint CP1, is informed to desist from the conversion be the centralcontrol means SCP in a signalling message DIW. The control means BSCalso reports the reception of the signalling message DIW by returning asignalling message DIWA.

After removal of a redundant transmission path in the arrangementaccording to FIG. 3, the arrangement according to FIG. 2 arises in whichonly the two redundant transmission paths are now combined at the singlecombination point, which is also the interworking point. FIG. 4 showsthe signalling flow between the network elements after cleardown of anexisting transmission path. The signalling message DIW with the requestto no longer implement the conversion and the signalling message DIWAfor acknowledgment of the request are exchanged between the centralcontrol means SCP and the switching equipment LE that contained theprevious interworking point the combination point CP2. The centralcontrol means SCP transmits the signalling message IWR to the controlmeans BSC that comprises the sole combination point CP1 as newinterworking point IWP. The signalling message IWR contains the requestfor the conversion of the mobile radiotelephone network-specificallyencoded information contained in the transmission frame. After receptionof the request, the control means BSC returns the signalling messageIWRA to the central control means SCP for acknowledgment.

The invention is not limited to the particular details of the apparatusdepicted and other modifications and applications are contemplated.Certain other changes may be made in the above described apparatuswithout departing from the true spirit and scope of the invention hereininvolved. It is intended, therefore, that the subject matter in theabove depiction shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A method for transmitting information in auniversal transmission network having mobile radiotelephonenetwork-specific functions and fixed network-specific functions,combining at combination points common information that is transmittedin transmission frames between the transmission network and aradiotelephone subscriber station on different redundant transmissionpaths that are set up parallel via a radio transmission interface to thetransmission network, at the combination points respectively twotransmission paths being combined to a single transmission path in onetransmission direction and an individual transmission path being dividedinto two transmission paths in the other transmission direction;selecting a respective combination point, at which two last transmissionpaths are combined or a single transmission path is divided, by acentral controller in the transmission network, which is informed of allcombination points, as sole interworking point in the transmissionnetwork at which mobile radiotelephone network-specifically encodedinformation contained in a transmission frame is converted into fixednetwork-specifically encoded information.
 2. The method according toclaim 1, wherein given change of the interworking point due to a setupof an additional transmission path or due to a cleardown of an existingtransmission path, a further combination point that becomes a newinterworking point is requested to implement conversion of theinterworking point being requested by the central controller in asignaling message.
 3. A method according to claim 2, wherein thecombination point that previously implemented a conversion is requestedby the central controller in a signaling message to desist from theconversion.
 4. A method according to claim 1, wherein the centralcontroller is a service control point that is involved in thetransmission network for executive sequencing of services.
 5. A methodaccording to claim 1, wherein the interworking point is located in oneof a radio or switching equipment of the transmission network.
 6. Amethod according to claim 1, wherein mobile radiotelephonenetwork-specifically encoded information is transmitted in thetransmission frame; and wherein an information cell to be transmittedaccording to asynchronous transfer mode is respectively employed as thetransmission frame.
 7. A method according to claim 1, wherein mobileradiotelephone network-specifically encoded information is transmittedin the transmission frame; and wherein an information block to betransmitted according to a synchronous transfer mode is respectivelyemployed as the transmission frame.